AT&T wouldn't do it.
So tried a promising unlocker.
They tried and failed to get a code.
Running out of time, one last attempt. Samsung codesource.
Normally a weekday service but they ran it over the weekend for me. Still elusive, so they said they would rerun it on a more powerful but slower program. Took a few days but they got it, and it worked. Off to Europe in the morning with an unlocked phone. Great! Thanks guys!